Sole plate coating for a fabric pressing device

ABSTRACT

A fabric pressing device has a composite sole plate with a base component of metal or similar thermally conductive material that is coupled to the heat source of the pressing iron, and a layer of ceramic bonded to the base component. The ceramic layer has a planar fabric pressing surface that preferably has a smoothness of about a nominal two micrometers surface roughness or better. That ceramic surface is highly resistant to wear and to impact, is easy to clean, and has excellent dynamic and static frictional characteristics on textile fabrics.

This invention relates to fabric pressing devices.

Manual pressing devices preferably are light in weight and should slideeasily across the fabric so that they can be easily manipulated duringpressing, and the fabric contacting surface should impart the desiredsmoothing action on the fabric. Such fabric pressing devices have a heatsource that heats a sole plate (typically of metal or plastic) whichdefines the surface that contacts the fabric to be pressed. Thetemperature of the sole plate typically is adjustable as a function ofcharacteristics of the fabric to be ironed, and as pressing action isfrequently enhanced with the presence of steam, the pressing devicefrequently includes a water chamber and means for generating steam whichis discharged through ports in the sole plate during the pressingaction. In order to improve the manipulability of the pressing device onthe fabric, and to reduce weight (make the pressing device easier tohandle), the fabric pressing surfaces of such devices are frequentlymade of aluminum and/or coated with a low friction polymeric materialsuch as polytetrafluoroethylene. Such surfaces are easily and frequentlyscratched or marred, for example by efforts to clean the soleplatesurface to remove adhering foreign substances or by the pressing actionitself (due for example to grit embedded in the fabric being pressed),such scratching or marring tending to reduce the effectiveness of thefabric smoothing action of the pressing device.

In accordance with one aspect of the invention, there is provided afabric pressing device that has a composite sole plate with a basecomponent of thermally conductive material that is coupled to the heatsource of the pressing iron, and a layer of ceramic bonded to the basecomponent, the ceramic layer having a thickness in the range of aboutfifty to about five hundred micrometers and a smooth fabric pressingsurface that preferably has a smoothness of at least about a nominal twomicrometers surface roughness. That ceramic surface is highly resistantto wear and to impact and has excellent dynamic and static frictionalcharacteristics. The ceramic layer does not have adverse effect on theheat-up rate of the device, that heat up rate being substantially thesame as that of an iron with an uncoated (bare aluminum) soleplate. Inparticular embodiments, the ceramic layer is composed of ceramicparticles (for example, a carbide, a boride, or a metal oxide such asalumina, cobalt oxide, titania or mixtures of such ceramics) that arebonded together, the ceramic particles having a hardness of more thanone thousand DPHN (ten gram load).

In accordance with another aspect of the invention, there is provided amethod of manufacturing a fabric pressing device comprising the steps ofproviding a base component of thermally conductive material that isadapted to be coupled to the heat source of the pressing device and thathas a rough surface, adhering a layer of ceramic material having athickness in the range of about fifty to about five hundred micrometersto the rough surface of the base component, and smoothing the surface ofthe adhered layer of ceramic material to provide a planar fabricpressing surface. While the ceramic layer may be adhered by varioustechnologies such as chemical vapor deposition or sputtering, inpreferred embodiments, after the surface of the base component isroughened by grit blasting to provide a resulting roughened surface thathas a typical peak-to-valley dimension of at least about tenmicrometers, ceramic particles that are entrained in and heated by aplasma stream are sprayed on the roughened base component surface, theheated particles deforming on impact on the base component to form abonded ceramic layer that has a density of at least about eightypercent. The surface of the resulting ceramic layer is then smoothed bypolishing to a surface quality of at least about one micrometer surfaceroughness.

In a particular embodiment, the fabric pressing iron device includes abody which contains a water holding chamber and steam generating means,and the sole plate has ports in communication with the steam chamber forpassing steam to the sole plate surface for contact with the fabricbeing ironed, a heating element is embedded in the base component, and apower supply conductor and a control are provided for adjusting thetemperature of the sole plate. The pressing iron is easy to manipulate,its sole plate is highly resistant to wear and impact, is easy to clean,and the frictional characteristics of the fabric-ceramic material pairare comparable or superior to commercially available pressing irons withpolymeric coatings on their sole plates.

Other features and advantages of the invention will be seen as thefollowing description of particular embodiments progresses, inconjunction with the drawings, in which:

FIG. 1 is a perspective view of a fabric pressing iron device inaccordance with the invention;

FIG. 2 is a plan view on the sole plate of the pressing iron device ofFIG. 1;

FIG. 3 is a photomicrographic cross sectional view of the sole plate ofthe pressing iron device of FIG. 1 before polishing;

FIG. 4 is a photomicrographic view of the polished sole plate surface ofthe pressing iron device of FIG. 1;

FIG. 5 is a graphical presentation of comparative static frictionalforces of of pressing iron devices in accordance with the invention andprior art pressing iron devices; and

FIG. 6 is a graphical presentation of comparative dynamic frictionalcharacteristics of pressing iron devices in accordance with theinvention and prior art pressing iron devices.

DESCRIPTION OF PARTICULAR EMBODIMENTS

Shown in FIG. 1 is a fabric pressing iron device that has a body 10 withsole plate structure 12 and manipulating handle 14. Formed in body 10 isa chamber for storing water (that is filled and emptied through port16). A heating element in body 10 is in intimate contact with the soleplate 12 and is energized via power supply cord 18 and controlled bytemperature adjusting disc 20 to vary the temperature of sole plate 12.The pressing iron also includes steam control 22. Formed in the bottomof sole plate 12 (as indicated in FIG. 2) is an array of ports 24through which steam is flowed to enhance pressing effectiveness.

Sole plate 12 is composed of ceramic layer 28 that is bonded to theunderlying heat distributing aluminum base 30 (as shown in thephotomicrographic sectional view of FIG. 3). The composite sole platestructure 12 is formed by cleaning and roughening aluminum base 30 witha grit blast (the resulting roughened surface having a typicalpeak-to-valley dimension of about twenty micrometers) and then applyinga layer of ceramic material to a thickness of up to about two hundredmicrometers. In the embodiment shown in FIGS. 3 and 4, alumina in theform of ten micrometer spheres is heated in a plasma stream generated bya plasma spray gun and sprayed on base 30, the heated spheres deformingupon impact to disk shape of about one micrometer thickness andproviding a bonded ceramic layer 28 that has a density of about ninetypercent.

After alumina layer 28 has been deposited, its surface is smoothed witha silicon carbide embedded nylon wheel and then polished with diamondpaste to a nominal surface roughness of about one micrometer. Aphotomicrograph of the polished ceramic (alumina) surface is shown inFIG. 4, the dark spots in the photomicrograph of FIG. 4 being voids orpores. The alumina particles have a hardness of about 2,400 dphn (tengram load). The polished sole plate surface 32 heats up at rates thatare substantially the same as that of uncoated (bare aluminum)soleplates, is easy to clean and is highly resistant both to wear and toimpact.

Frictional characteristics of pressing iron devices with ceramic soleplates in accordance with the invention were evaluated or compared withsimilar fabric pressing devices with aluminum sole plates and withaluminum sole plates that have polymeric coatings such as Teflon (PTFE)containing coatings. Each of the compared irons had a weight of about1.1 kilograms and their frictional characteristics were measured on avariety of textile fabrics and at different pressing temperatures.Comparisons of frictional characteristics of those pressing iron deviceson linen fabrics are set forth in FIGS. 5 and 6, the comparisons shownin FIG. 5 being of static characteristics and the comparisons in FIG. 6being of dynamic characteristics. In those Figures, the frictionalcharacteristics of the prior art aluminum sole plate are represented bycircles, the characteristics of the composite ceramic sole plate inaccordance with the invention are represented by squares, and thefrictional characteristics of Teflon (PTFE) containing coatings onaluminum sole plates are represented by "X"s. While the staticfrictional characteristics on linen of the three sole plates at ambienttemperature are substantially the same (at or slightly above 200 gramsof force), the static friction characteristics of the ceramic compositesole plates at 125° C. and 175° C. on linen were less than either ironswith aluminum sole plates or irons with PTFE coated sole plates. Asshown in FIG. 6, the dynamic frictional characteristics of the PTFEcoated sole plates on linen were significantly better at roomtemperature but the composite ceramic sole plate dynamic frictionalcharacteristics on linen at 125° C. and at 175° C. were substantiallythe same as the PTFE coated sole plates and better than the dynamicfrictional characteristics of the aluminum sole plates.

Set forth in the following table is a comparison of static and dynamicfriction (pulling forces in grams) of the three types of sole plates onsilk at 110° C.:

                  TABLE 1                                                         ______________________________________                                        Sole Plate      Static  Dynamic                                               ______________________________________                                        Teflon          166     106                                                   Aluminum        144     106                                                   Alumina         134     114                                                   ______________________________________                                    

As will be noted, the static frictional characteristics of the compositeceramic (alumina) sole plates were better than either the Teflon coatedsole plates or the aluminum sole plates, and the dynamic frictionalcharacteristics were substantially the same.

Table 2 sets out a similar comparison of static and dynamic frictionalcharacteristics of the three types of pressing devices on denim at 175°C.:

                  TABLE 2                                                         ______________________________________                                        Sole Plate      Static  Dynamic                                               ______________________________________                                        Teflon          140     90                                                    Aluminum        136     116                                                   Alumina         106     80                                                    ______________________________________                                    

As can be seen from Table 2, both the static and dynamic frictionalcharacteristics of the composite ceramic (alumina) sole plates weresuperior to the frictional characteristics of both the sole plates withPTFE (Teflon) containing coatings and the aluminum sole plates. Asimilar comparison of static and dynamic frictional characteristics(average of five tests each) on denim at 160° C. of three differenttypes of composite soleplate pressing devices (ceramic layers ofalumina, cobalt oxide, and an alumina-titania mixture) with acommercially available iron that had a Teflon-containing coating on analuminum soleplate produced similar results--both the static and dynamicfrictional characteristics of the composite metal-ceramic soleplateswere superior to the frictional characteristics of the iron with analuminum soleplate with a PTFE (Teflon) containing coating, while thestatic and dynamic frictional characteristics of an iron with acomposite metal-titania soleplate was slightly inferior to thefrictional characteristics of the iron with a PTFE (Teflon) containingcoating on an aluminum soleplate. Pressing devices in accordance withthe invention have sturdy soleplate surfaces that are easy to clean.While the frictional characteristics of soleplate surfaces on textilefabrics appear to be complex functions of temperature, the nature of thetextile fabric and the soleplate material, the frictionalcharacteristics of pressing devices in accordance with the invention areequal to or better than commercially available pressing devices withpolymeric coatings (such as PTFE) on their soleplate surfaces.

While particular embodiments of the invention have been shown anddescribed, various modifications will be apparent to those skilled inthe art, and therefore is not intended that the invention be limited tothe disclosed embodiment or to details thereof, and departures may bemade therefrom within the spirit and scope of the invention.

What is claimed is:
 1. A fabric pressing device that has a compositesole plate, said fabric pressing device including a body, a heatingelement in said body, a power supply conductor for supplying power tosaid heating element, and a control for adjusting the temperature ofsaid heating element, and said composite sole plate comprising a basecomponent of thermally conductive material that is coupled to saidheating element, and a layer of ceramic bonded to said base component,said ceramic layer being composed of ceramic particles that are bondedtogether, said ceramic layer having a thickness in the range of aboutfifty to about five hundred micrometers and having a smooth fabricpressing surface, said smooth fabric pressing surface having asmoothness quality of about two micrometers surface roughness or better.2. The device of claim 1 wherein said ceramic is selected from the groupconsisting of carbides, borides and oxides, and mixtures of suchceramics.
 3. A fabric pressing device that has a composite sole plate,said composite sole plate comprising a base component of thermallyconductive material that is coupled to the heat source of the pressingiron, and a layer of ceramic bonded to said base component, said ceramiclayer having a thickness in the range of about fifty to about fivehundred micrometers and a smooth fabric pressing surface, said ceramicparticles having a hardness of more than one thousand DPHN (ten gramload), the heat-up rate of said ceramic layer being substantially thesame as that of said base component without said ceramic layer, and saidlayer being composed of ceramic particles that are bonded together andhaving a density of at least about eighty percent.
 4. The device ofclaim 3 wherein said fabric pressing iron device includes a body whichcontains a water holding chamber and steam generating means, and saidsole plate has ports in communication with said steam chamber forpassing steam to said sole plate surface for contact with the fabricbeing ironed, a heating element embedded in said base component, a powersupply conductor for supplying power to said heating element, and acontrol for adjusting temperature of said sole plate.
 5. The device ofclaim 4 wherein said ceramic is a metal oxide.
 6. A fabric pressingdevice comprising a body which contains a water holding chamber andsteam generating means and a composite sole plate, said composite soleplate comprising a base component of thermally conductive material, anda layer of ceramic bonded to said base component, said sole plate havingports in communication with said steam chamber for passing steam to saidsole plate surface for contact with the fabric being ironed, a heatingelement imbedded in said base component, a power supply conductor forsupplying power to said heating element, and a control for adjustingtemperature of said sole plate, said ceramic layer having a thickness inthe range of about fifty to about five hundred micrometers and a smoothfabric pressing surface, said ceramic layer being composed of ceramicparticles that have a hardness of more than one thousand DPHN (ten gramload), and that are bonded together, the heat-up rate of said ceramiclayer being substantially the same as that of said base componentwithout said ceramic layer, and said layer having a density of at leastabout eighty percent.
 7. The device of claim 6 wherein said ceramic is ametal oxide and the surface of said ceramic layer has a smoothness ofabout one micrometer surface roughness or better.